As described on page 96 in “W-CDMA Mobile Communication System” (supervising editor Keiji Tachikawa, published by Maruzen Co., Ltd. on Jun. 25, 2001) standardized by 3GPP (3rd Generation Partnership Project) which is a standardization association of industry, a third generation mobile network to which W-CDMA (Wideband-Code Division Multiple Access) radio technique is applied includes a radio area network (called RAN) and a core network (called CN). The radio area network related to this invention is a network in which radio control and station movement control depending on W-CDMA (Wideband-Code Division Multiple Access) radio technique is performed.
FIG. 11 shows an architecture diagram of the radio area network. 1 denotes a packet switchboard belonging to the core network (CN), and 2 denotes a voice switchboard belonging to the core network (CN). 3a-3c denote base station controllers (RNC) belonging to the radio area network (RAN), 4a-4d denote base stations (NodeB) belonging to the radio area network (RAN). 5 denotes a mobile station (MS).
FIG. 12 outlines an operation when transmission is originated from the mobile station (MS) in the radio area network (RAN). When the mobile station (MS) 5 starts voice/packet communication, the mobile station (MS) 5 requests the base station controllers (RNC) 3a-c to allocate a radio signaling resource which is necessary for transmission of signaling at first. This request is sent to the base station controllers (RNC) 3a-c through the base stations (NodeB) 4a-d which terminate this channel using a radio common channel which can be used commonly by all of the mobile stations (MS) 5. By this request, the base station controllers (RNC) 3a-c allocate a radio individual channel used by the mobile station (MS) 5 for transmission of signaling, and notify the base stations (NodeB) 4a-d of radio individual channel information. In this way, resources, e.g., spread code, frequency, etc. is allocated to the mobile station (MS) 5. When the resources for the mobile station (MS) 5 in the base stations (NodeB) 4a-d have been secured, the base station controllers (RNC) 3a-c notify the mobile station (MS) 5 of this radio individual channel information. Accordingly, the radio signaling resource has been allocated.
After then, the mobile station (MS) 5 notifies the core network (CN) of a request to originate transmission of a packet or to originate transmission of voice using this radio signaling resource. By this request, the core network (CN) requests the base station controllers (RNC) 3a-c to allocate a radio call resource used for packet communication or voice call. By this request, the base station controllers (RNC) 3a-c determine to increase the radio individual channel used, and notify the base stations (NodeB) 4a-d of this. When the base stations (NodeB) 4a-d have added the resources for the mobile station (MS) 5 at the base stations (NodeB) 4a-d, the base station controllers (RNC) 3a-c notify the mobile station (MS) 5 of this radio individual channel information. Accordingly, the radio call resource has been allocated. Then, the mobile station (MS) 5 becomes able to perform the packet communication or voice call.
In FIG. 12, a flow concerning information for security and authentication sent and received between the mobile station (MS) and the radio area network (RAN)/core network (CN), a flow concerning various synchronization/timing control, and sending and receiving of various information between the mobile station (MS) and the core network (CN) are omitted as they are not directly related to this invention.
Further, concerning radio area network (RAN) architecture in the future, MWIF (Mobile Wireless Internet Forum) is proposing Open RAN Architecture (MTR007v1.0.0). Mapping of open radio area network (OPEN RAN) and 3GPP radio area network (3GPP RAN) described on page 52 of this document is illustrated in FIG. 13. In FIG. 13, the base station controllers (RNC) 3a-c are divided into two planes, i.e., bearer plane (Bearer Plane) for handling user traffic and control plane (Control Plane) for controlling the mobile station (MS) and the base station (NodeB). Further, each of them is split into a part for handling cell resources, described as CRNC/DRNC and a part for handling resources allocated to the mobile station (MS), described as SRNC. This architecture aims at optimally arranging many functions provided in the base station controller (RNC) in present condition, and suggests that there is a possibility to decompose and restructure the present architecture.
This invention intends to solve the problem in the open radio area network architecture with presumption that the open radio area network (RAN) will develop based on the open radio area network architecture (Open RAN Architecture) of MWIF. Particularly, in the open radio area network architecture, the control plane (Control Plane) of the base station controller (RNC) is divided into a part for controlling the cell resources and a part for controlling each of the mobile stations (MS), and each of the parts is provided additionally according to a number of cells or a number of the mobile stations (MS). This suggests that control of the base station controller (RNC) is distributed to functions of cell control and mobile station (MS) control, and also suggests that a load is distributed in each level of the cell control or the mobile station (MS) control. The open radio area network architecture describes this method to distribute functions, however does not regulate a load distributing system of each of the functions. It is a subject of this invention to provide the load distributing system which can be applied to this new area network architecture.